second through fourth order, loop-forming veins which promote 

 its "festooned" appearance due to the nearly complete closure of 

 the intramarginal, loop-forming veinlets. 



EPiDtRMis: Epidermal cells typically are polygonal in surface 

 view with straight lateral walls. The cells are larger in the upper 

 epidermis, although their sizes are normally uniform within each 

 surface layer. Epidermal cell walls appear slightly sinuous only 

 rarely in occasional specimens of E. novogranateme var. novo- 



granatense. . . 



Stomata are of the paracytic type, with their paired subsidiary 



cells aligned parallel to the long axis of the guard cells, and are 

 restricted to the lower epidermis in all leaves (Plate 37). 

 Statistical data for stomatal density, frequency and guard cell 

 size are summarized in Table 5. 



Epidermal papillae are prominent and abundant but confined 

 to the lower surface of the leaves. They arc always absent from 

 the guard cells and associated subsidiary cells of the stomatal 



apparatus. 



crystals: Vein-associated, prismatic (rhomboidal) crystals of 

 calcium oxalate may be abundant, sparse or absent in all coca 

 leaf varieties. Prismatic crystals also may occur in clusters of 

 anticlinally subdivided cells of the lower and upper epidermis in 

 all varieties. 



scLEREiDs: Foliar sclereids are typically absent from all 

 ultivated coca leaves but may be characteristic of other species 

 of Ervlhroxylum (Rury, 1981, 1982). 



FOLIAR 



C 



DISCUSSION 



LEAF STRUCTURAL PLASTICITY OF COCA LEAVES 



Light intensity, humidity and moisture availability may 

 influence profoundly the relative leaf size, form, vein thickness 

 and patterns, as well as stomatal and veinlet terminus numbers 

 in all varieties of cultivated coca (Rury, 1981, 1982). Classical 

 shade-leaf as opposed to sun-leaf structural differences may be 

 found within each variety in relation to microhabitat differences 

 experienced by individual plants and leaves. Humid and shady 



310 



